Automatic brake for elevators.



P. KESTEN 64 H. OSBORNE.

AUTOMATIC BRAKE FOR ELEVATORS. APPLICATION FILIED MAY 6.1913.

1 1 73,438. Patented Feb. 29, 1916.

l WM w UNITED {STATES P TENT orrron.

I PAUL KESEIJEN, .OF NUREMBERG, AND IdIEINRICH OSBORNE, OF-CHARLOT 'JJIEJIEII'IBURG',

GERMANY, ASSIGNORS TO SIEMENS-SCHUCKERT-WERKE, G. M. B. H., OF-BERLIN, I GERMANY, A CORPORATION OF GERMANY.

AUTOMATIC BRAKE For. ELEVATORS.REISSUED Specification of Letters Patent.

Patented Feb. 29, 1916.

Application filed May 6, 1913. Serial No. 765,839.

To all whom it may concern:

' Be it known that we, PAUL KEs'rnN and HEINRICH OSBORNE, citizens, respectively, of the German and the Austro-Hungarian Empires, and residing, respectively, at Nuremberg and Charlottenburg, nearBerlin, Germany, have invented certain new and useful Improvements in Automatic Brakes for Elevators, of which the following is a specification.

This invention relates to automatic brakes for electric elevators.

When elevators travel at high speeds and have to convey heavy loads it is difficult to stop at exactly predetermined points. In spite of quick-acting braking devices the highly loaded cage will always-travel a considerable distance-beyond the desired end position owing to its momentumwhen the distance of the required. position.

disconnecting contact-piece for the motor and for the application of the brake is so arranged that the elevator stops when running empty in the desired position. Such elevators are therefore frequently caused to travel at a reduced speed before they reach the stopping place, so that the brake is applied for only ashort distance both when the elevator is light and when it is fully loaded, whereby greater accuracy in reaching the correct stopping place is obtained.

Even when this method is used it is not possible to reach the prescribed point absolutely exactly. According in each instance to the magnitudepf, the load on the elevator the cage remains stationary within a certain On the otherhand, the described arrangement has the considerable disadvantage that the average speed of travel is materially diminished bythe high-speed ceasing prematurely.

A primary object of this invention is .to

providean automatic brake for elevators.

' such that there is no need to .reduce the speedbefore running to the stopping place. The, cage is to be able to travel at full speed as far as every stopping place, so that all loss. of time owing to premature slowing of the entire elevator is obviated. In the event'of the cagerunning past a predetermined limit, say in consequence of its mo- The reversal of the direction of rotation A of the motor, which is preferably driven by a controlling generator connected on the Leonard system, is brought about by the field of this generator being reversed. For example, this generator may be provided 6% with a separate field winding which is independent of the main windings and traversed by the current only when the cage travels past the desired end position and then in an opposite direction to that in which the current has previously traversed the main windings. In order to bring the magnetic field as rapidly as possible to its final value, large resistances may be connected in series with this auxiliary winding, so that the time constant ofthe circuit is very small. It is tobe understood,

however, that any other method of rapid excitation may be employed if desired.

After the direction ofrotation has been reversed and when the cage is traveling into its correct stopping position, in order to prevent theelevator-motor having to work against the action of the already applied K I brake, the brake-magnet which prevents the-8 5' application of the brake is preferably energized by the current used for reversing the excitation of the controlling generator. When the motor runs in the opposite direc- 1' f tion the brake is then taken off and applied '90 again only in the desired end position of. the lift. The improved automaticbrake for elevators according to our inventionwillnow be described with reference to the accompany- .95 ing drawing diagrammatically showing oneform of apparatus according to the invention. v

In the drawing, 1 designates the cage carried by the rope Qqvhich passes over the" pulleys 3 and 4 to the drum 5 driven by means of the gearing 6 and the shaft 11 by the driving motor 7. This motor having the shunt winding 8 is controlled by the gener ator 9 having the main field winding 10,

nected by the .eye 18 and the rod 19 with the lever 13. The one lever-arm 20 of a three-armed lever 20, 22, 25 carries the antifriction or guide roller 21, the second arm 22 of this lever is pivotally connected with the handle 23 of an end switch 24, and the third arm 25 of this lever is pivotally connected with the handle 26 of a second end switch 27.

In the position a of the cage shown in the drawing, 71. e., shortly before the cage moves into the desired position b, when it is still moving at the full working speed, the following circuit is closed terminal of a source of current 28, switch 24 and its contact plate 29, conductor 30, solenoid 31 of the brake-magnet 17, the conductors 32, 33, and the terminal of the source of current 28. The magnet 17 is consequently drawn into the solenoid 31 and the brake-block 14 is removed from the brake-disk 12.

In the desired position b of the cage the roller 21 has run onto the stop 34 mounted on the cage, so that the lever-arm 22 and the handle 23 are moved into the position b and the lever-arm 25 and the handle 26 into the position b. The above-mentioned circuit is consequently brokenand the brake is applied. When the cage 1 travels past the desired position b the roller 21 runs farther up the stop 34. In the, position 0 of the cage the lever-arm 22- andthe handle 23 aremoved from the positionfbl to oand the third lever-arm 25 and the handle 26 are moved from the position Zf'fto c". In this position the following circuit is closed. by the switch 2'Z:-the source of current 28,-

conductor 35, contact-plate 36 and switch 27, wire 37, the second'shunt winding 38 of the generator 9, resistance 39, the wire 33 and the source of current 28. The auxiliary winding 38 when energized will cause the reversal of the generator 9. The solenoid 31 of the magnet 17 is connected in parallel therewith over the contact-plate 36, the handle 26 of the switch 27 the contactplate 36, and the wires 40 and 32, so that the brake-block 14 is simultaneously removed from the disk 12. The motor 7 then changes its direction of rotation and lifts the cage 1 back into the desired position b, the three-armed lever 20, 22, 25 being likewise moved backward by the spring 41. The lever-arm 22 and the handle 23, and

tively, so that no current flows in the solenoid 31 or in the auxiliary field-winding 38 of the generator 9. The brake is again applied and the cage stops in the desired position b. When the disconnecting stop 34 returns, the three-armed lever 20, 22, 25 is returned by the spring 41 into its initial position so that the handles 23, 26 of the switches 24 and 27, respectively, are returned into their initial positions a and a", respectively, the brake being again released by the switch 24 as described above and the cage 1 being able to be moved forward or backward in known manner again.

Obviously the herein described apparatus can be used for any desired number of stopping places of the elevator; and also for both directionsrof travel.

We claim: 1. The combination with a controlling generator, and a motor driven thereby on the Leonard system, of an auxiliary field.- winding on said generator for reversing the field thereof, a cage of an elevator and means controlled by said cage for energizing said vfield winding when the cage has passed a predetermined point and deenergizing the same when the cage has returned to said point.

2. The combination witha controlling generator, a motor driven thereby on the- Leonard system and an electromagnetic brake for the motor, of a normally closed circuit including the winding of said electromagnetic brake, a normally open secon'd c1r-' cuit including an auxiliary field-winding on 7 brake for the motor, of a normally closed circuit including the winding of said electromagnetic brake, a normally open second circuit in parallel with said winding and including an auxiliary field-winding on said generator for reversing the field thereof, a cage of an elevator and means controlled by said cage for first opening the first circuit when the cage passes a predetermined point, then closing both this circuit and the second circuit when the cage has run beyond this'point, and finally reopening both of said circuits when the cage has returned thereto.

4. The combination with a controlling generator, and a motor driven thereby on the Leonard system, of an auxiliary fieldwinding on said generator for reversing the names to this specification in the presence of two witnesses.

PAUL KESTEN. HEINRICH OSBORNE.

Witnesses as to signature of Paul Kesten:

OSCAR BooK, RALPH W. Box. I Witnesses as to the signature of Heinric Obsorne:

WOLDEMAR HAU'PT, HENRY HASPER. 

